Reconciling Induced-Gravity Inflation in Supergravity With The Planck 2013 & BICEP2 Results

TL;DR

This paper extends induced-gravity inflation models in supergravity by incorporating additional fields and symmetries, achieving compatibility with recent BICEP2 results and Planck data through slight modifications of the Kahler potential.

Contribution

It introduces a generalized supergravity inflation model with specific symmetries and higher-order terms, enhancing tensor-to-scalar ratio predictions while maintaining subplanckian field excursions.

Findings

Tensor-to-scalar ratio can be increased to match BICEP2 results.

Inflationary observables are compatible with data with mild tuning.

Inflaton mass predicted near 10^14 GeV.

Abstract

We generalize the embedding of induced-gravity inflation beyond the no-scale Supergravity presented in arXiv:1403.5486 employing two gauge singlet chiral superfields, a superpotential uniquely determined by applying a continuous R and a discrete Zn symmetries, and a logarithmic Kahler potential including all the allowed terms up to fourth order in powers of the various fields. We show that, increasing slightly the prefactor (-3) encountered in the adopted Kahler potential, an efficient enhancement of the resulting tensor-to-scalar ratio can be achieved rendering the predictions of the model consistent with the recent BICEP2 results, even with subplanckian excursions of the original inflaton field. The remaining inflationary observables can become compatible with the data by mildly tuning the coefficient involved in the fourth order term of the Kahler potential which mixes the inflaton with the accompanying non-inflaton field. The inflaton mass is predicted to be close to 10^14 GeV.